Imaging systems may include an imaging member such as a photoreceptor. In many instance, the imaging member is formed using a coating material that includes a pigment for a charge-generating layer or photoconductive layer. For example, hydroxygallium phthalocyanine is a pigment with high sensitivity. However, using the pigment hydroxygallium phthalocyanine with current methods that form the charge-generating layer can cause a high dark decay and induce charge deficient spots.
There have been efforts to improve the performance of hydroxygallium phthalocyanine in cyclic stability, print quality, and coating quality by reducing the raw pigment and subsequent dispersion particle size of conventional pigments. For example, a useful polymorph Type V (hydroxygallium phthalocyanine (V)) has been converted from crude hydroxygallium phthalocyanine (hydroxygallium phthalocyanine (I)) by using a process of ball milling in the pigment using a solvent. Moreover, different hydroxygallium phthalocyanine (V) synthesis and grinding routes have been used to reduce particle size. Current pigments used in coating materials that form photoreceptors are highly sensitive and composed of various particle sizes.